Starting and operating circuits for fluorescent lamps



Aug. 2, 1955 w. s. H. HAMILTON 2,714,691

STARTING AND OPERATING CIRCUITS FOR FLUORESCENT LAMPS Original Filed Feb. 15, 1950 INVENTOR IV/W/kvm 61/6. Ham/Won ATTORNEY.

operating circuits for 2,7 14,6 91 Patented Aug. 2, 1955 STARTING AND OPERATING CIRCUITS FOR FLUORESCENT LAMPS William S. H. Hamilton, Larchmont, N. Y.

3 Claims. (Cl. 315103) This application is a division of my prior application Serial No. 144,345, filed February 15, 1950.

This invention relates to improvements in starting and fluorescent lamps, particularly those operated on 60-volt and 110-volt D. C. and A. C. sources of current supply, such as lamps of the 12", "i -S (1 dia.), T-l2 (1 /2 dia.), 18", T12 (1 /2 die.) and 24", T-12 (1 /2 dia.) types, but which are adapted for use in connection with other hot-cathode lamps having like operating characteristics.

One object of the invention is to provide a novel and improved circuit organization employing a thermo-electromagnetic starter, preferably but not necessarily of plug-in type, for supplying preheating and operating currents to the lamp in such a manner as to secure quick starting and restarting actions.

Another object of the invention is to provide a starter embodying a time delay thermostatic switch and a relay embodying a switch member operating in conjunction Still another object of the invention is to provide a starter of the described type which will permit of a practically instantaneous restarting of the lamp which has been turned off and then turned on again shortly, regardless of the position of the thermal switch.

Still another object of the invention is to provide a a plug-in can or casing same size as that of a conventional starter, such as the FS-44 starter, and used in the same or a similar socket with little or no circuit wiring changes.

With these and other objects in view, which will appear in the course of the subjoined description, the invention consists of the novel features of construction, combination and arrangements of parts hereinafter more fully set forth, and as shown in the accompanying drawings, in which:

Figure 1 is a schematic diagram of one form of circuit as adapted for operation with a D. C. fluorescent lamp and employing a thermo-electro-magnetic starter embodying my invention, showing the parts in normal starting position.

Figure 2 shows an enlarged detail view of the circuit disclosed in Figure 1, showing the starter switches as arranged when the lamp is operating.

Referring now particularly to the drawings, 1 represents the gas containing envelope of the lamp having the negative cathode and positive filamentary electrodes 2 and 3, respectively, at least one of which is adapted to be preheated to start the lamp. In the case of a circuit as shown, which is designed to operate primarily filament,

tors or leads 4 and 5 forming with the electrodes an operating circuit, which conductors are adapted to be connected at points 6 and 7 to the terminals of a line circuit adapted to be opened and closed in practice by suitable means. In the conductor 4* between the electrode 3 and terminal 6 are arranged a reactance 8 and a ballast lamp 9, which may be of any suitable type, and located in the output conductor 5* is the coil 10 of the relay of the combined thermal and relay switch device, hereinafter described.

Extending from the conductor 4* h at a point between t e reactance 8 and the lamp is a preheating conductor 14 normally connects through its contacts 15 15 the output end of section 11 with the input end of section 12 and in the output end of branch 13 is a heating resistance 19*. An arc suppressing condenser 20 extends across the adjacent ends of sections 13 and 13 to suppress or reduce the arcing at the contacts 15 15 of the relay switch when breaking the circuit through the reactance 8 Connected in conductor 5 at opposite sides of the coil are connections 21 of a shunt circuit normally closed by the contacts 17 17 of a second relay switch 16 and the contacts 22 of a thermostatic when the filament 2 is sufficiently heated, by the opening of the contacts 22 of the thermostatic time delay switch, which causes preheating current to energize coil 10 and open its contacts 15 15 and 17 Breaking of the preheating circuit by switch member 14* causes the lamp if in good condition to fire and establish the operating circuit in which current flows from terminal 6 of the line, through the reactance 8 ballast lamp 9 conduccircuit around the coil 10* due to the contacts 17*, 17 of switch 16* being open. Thus the lamp will continue to operate so long as the line circuit is closed and upon its being opened, switches 1 1i will immediately reclose so as to be ready for another starting action as soon as the line circuit is reclosed.

be enclosed within a can or plug-in container casing having plugany other suitable type of unitary starter adapted to fit within a can of'the same size as the 'can of the well known FS-44 starter. By this means a combined thermostatic switch and relay starter embodying my invention may be used in connection with installed lamps of the types described and'other similar types with little or no rewiring. A further advantage of this structure is that, if mounted in an FS44 starter socket, it will be reversible as to position, as said shocket is so arranged by the size of its openings to receive the prongs of the starter in only two positions, either of which gives proper operation of the circuit.

The parts are normally arranged as shown in Fig. 1 to establish the starting circuit to supply preheating current to the lamp when the line circuit is closed.

It is to be understood that in the circuit organization shown the positive filament may be short-circuited or left open-circuited depending on the characteristics of the particular lamp used in the circuits.

It is also to be understood that while, for convenience in use, the switches and their connections are preferably placed in a starter can, which gives practical advantages, these parts, within the scope of my invention, may be placed partly within and partly without the can. It is also to be understood that While the circuit organizations are shown for example as being designed for use in connection with D. C. lamps, they may with little or no changes or suitable changes be used in connection with A. C. lamps.

Having thus described my invention, 1 claim:

1. In a system for supplying preheating and operating current to an electric discharge device having at least one filamentary electrode, an electromagnetic switch comprising two normally closed contact means and an operating winding, a thermal switch comprising normally closed contacts and an operating heater, means including an inductance ballast and said winding for connecting said electrodes with a source of current supply, a preheating circuit capable of producing firing temperature electrode heating connected across said device, said circuit including in series connection the electrode which is to be preheated, the first of said contact means, the said heater and the winding of said electromagnetic switch, and a circuit in shunt around said winding and including in series connection said thermal switch and the second of said contact means so that when said thermal switch opens it introduces said winding into the said preheating circuit causing operation of said electromagnetic switch, the opening of the first contacts thereof breaking the preheating circuit rapidly and causing the discharge device to fire by an induced voltage produced by said ballast and maintaining the preheating circuit open and the heater of said thermal switch cut off during the operation of the discharge device.

2. A system for supplying preheating and operating current to an electric discharge device as claimed in claim 1 in which the first contact means of the electromagnetic switch and the heater of the thermal switch are connected in series between one side of the supply source and one terminal of the electrode to be heated, the opposite terminal of said electrode being connected to the opposite side of the supply source through the winding of the electromagnetic switch.

3. In a starting device for electric discharge lamps having at least one filamentary electrode, the combination comprising an electromagnetic switch having an operating winding and two normally closed contact means, one of which is included in a shunt circuit across said winding, a thermal switch having normally closed contacts included in said shunt circuit, and a heater located to actuate said contacts to open position when heated and connected in series with the second of said normally closed contact means of said electromagnetic switch, and preheating circuit means including in series connection the electrode to be preheated, said heater and both of said normally closed contact means.

References Cited in the tile of this patent UNITED STATES PATENTS 

